Malignant Perineurioma Research Articles

Malignant perineurioma derived from the retroperitoneum with an aggressive clinical course: a case report

BackgroundMalignant perineurioma is a rare malignant counterpart of perineurioma derived from perineural cells. Resection is the primary option for the treatment of malignant perineuriomas; however, patients often develop recurrence after resection, and effective treatment for advanced or recurrent lesions needs to be established. This report describes a 51-year-old female with a rare malignant perineurioma in the retroperitoneum, which contributing valuable insights to the literature.Case presentationThe patient presented with abdominal distension and the imaging work-up revealed a huge hemorrhagic tumor in the retroperitoneum and obstruction of inferior vena cava by the tumor. The patient underwent surgery retrieving the tumor combined with left hemiliver and retrohepatic vena cava, which confirmed the diagnosis of a malignant perineurioma based on histopathological and immunohistochemical examination. Cancer gene panel testing identified mutations in NF2. Radiotherapy was administered for peritoneal dissemination 2 months after surgery, and the patient died from disease progression 6 months after surgery.ConclusionsThis rare case highlights the challenges in managing retroperitoneal malignant perineuriomas. The aggressive characteristics and limited treatment options for advanced malignant perineuriomas underscore the need for understanding the pathogenesis and developing effective systemic therapies. The identification of an NF2 mutation provides significant insights into potential therapeutic target.

Clinical and cytohistomorphological evaluation of peripheral nerve sheath tumours with special reference to immunohistochemical diversity in a tertiary care hospital

Peripheral Nerve Sheath Tumours (PNST), though have a frequent prevalence, are diagnostically challenging. There is a wide spectrum of lesions ranging from benign entities like neurofibroma, Schwannoma, perineurioma to malignant entities like malignant peripheral nerve sheath tumours (MPNST), malignant granular cell tumour and malignant perineurioma. Since there is an overlap with other spindle and round cell tumours, IHC and molecular studies are needed to provide a clear distinction between different tumour types. It was a 5 years observational study (3 years retrospective and 2 years prospective) conducted in the Department of Pathology, JNMCH, AMU from 2015-2020. . History and relevant clinical findings were retrieved from the archives of both the Histopathology and Cytopathology Lab. Imprints as well as FNA smears were included from Cytopathology Lab and biopsies and resection specimen from Histopathology Lab. Immunohistochemistry was applied wherever necessary. A total of 82 cases were diagnosed over a 5 year period out of which 70 were benign and 12 malignant. Male preponderance was seen. Benign tumours comprised mostly of Neurofibroma and Schwannoma and there were 12 cases of MPNST. Correlation was established between Cytopathological and Histopathological findings and IHC, mostly S100 proved useful in differentiating it from other malignant spindle cell tumours. The differential diagnoses of these tumours has always posed a problem given their monotonous appearance and clinical overlap. This study, therefore, aims to analyse the diverse morphological features of Peripheral Nerve Sheath Tumours in the light of cytopathological and histopathological findings and immunohistochemistry.

Sporadic Malignant Perineurioma: A Rare Diagnosis Among Malignant Peripheral Nerve Sheath Tumors

Malignant perineurioma is a rare subset of malignant peripheral nerve sheath tumors (MPNSTs) with ultrastructural and immunohistochemical features of perineurial differentiation, distinguishing it from other MPNSTs, which typically demonstrate Schwannian features. The clinical course and prognosis of this rare tumor is not well defined. The electronic medical records were searched for patients with a diagnosis of MPNST. Patients with a pathologic diagnosis of malignant perineurioma or MPNST with perineurial features were identified and further evaluated. Five patients with malignant perineurioma, or MPNST with perineurial features, were identified. Four patients (2 male and 2 female) were included with tumors associated with a common digital nerve, small muscular branch to the deltoid, sciatic nerve, and accessory nerve. One patient with the pathology diagnosis meeting inclusion criteria was excluded, as no clinical information was available for this patient. Patients in our series presented at varied stages of disease. Clinical courses after diagnosis of malignant perineurioma, where follow-up was available, were largely uncomplicated with regard to recurrence and metastatic disease. Careful follow-up is indicated, and further work is needed to characterize the clinical course of these rare tumors.

Malignant perineurioma (malignant peripheral nerve sheath tumor with perineural differentiation)

The great majority of malignant peripheral nerve sheath tumors (MPNST) exhibit Schwannian differentiation. In recent years, a subset of perineurial MPNST (malignant perineurioma) has been identified based on their histologic, immunohistochemical and ultrastructural features. Immunopositivity for epithelial membrane antigen (EMA), glut-1 and claudin-1, is characteristic. Such tumors must be distinguished from benign perineurioma and a variety of atypical or malignant soft tissue tumors featuring EMA positivity. Herein, we report a perineurial MPNST involving the buttock of a 42-year-old woman. Nerve involvement was noted. The clinicopathologic features of reported examples are ummarized and key differential diagnoses are discussed.

Low‐grade malignant soft‐tissue perineurioma: Interphase fluorescence in situ hybridization

Perineuriomas are usually benign soft-tissue tumors that arise from perineurial cells of the peripheral nerve sheath. Low-grade malignant perineurioma is a rare type of perineurioma, presenting with infiltrative growth, low mitotic activity, and a lack of necrosis. This report describes a case of low-grade malignant perineurioma in a 60-year-old man who presented with a growing tumor on the dorsal side of his left wrist. The tumor was surgically excised and showed no adhesion to the surrounding muscle and no continuity with nerves. There was no evidence of recurrence or metastases 12 months after surgery. Histology indicated that the tumor contained hypercellular and hypocellular areas with spindle-shaped cells proliferating in storiform patterns or perivascular whorling. There was moderate infiltrative growth into the surrounding tissue. There was an evident central infarction but no coagulative necrosis. Mitotic figures were observed at 5/10 high-power fields. On immunohistochemistry tumor cells were found to be positive for epithelial membrane antigen, glucose transporter protein 1, and claudin-1. Approximately 18.4% of tumor nuclei were labelled for Ki-67. Interphase fluorescence in situ hybridization on paraffin sections indicated a loss of chromosome 13. This suggests that chromosome 13 abnormalities could also be involved in perineurioma with low-grade malignant potential.

Evaluation of perineurial differentiation in epithelioid sarcoma

To investigate the differentiation pattern of epithelioid sarcoma in terms of perineurial and endothelial differentiation, and its relationship to that of meningioma. Nine cases of epithelioid sarcoma and five cases of meningioma were studied in an immunohistochemical analysis of 'perineurial' antigens [GLUT-1, claudin-1, epithelial membrane antigen (EMA) and VE-cadherin] and of 'endothelial' antigens not present on normal perineurium (CD34, CD31, Fli-1). Both epithelioid sarcoma and meningioma showed frequent expression of the perineurial markers GLUT-1, claudin-1 and EMA. VE-cadherin was identified in one of five meningiomas, and in the only case of epithelioid sarcoma in which suitably fixed material was available. CD34 was expressed by all epithelioid sarcomas studied but by none of the meningiomas. Fli-1 was present in a substantial majority of epithelioid sarcomas and by all the meningiomas. CD31 was not detected in any epithelioid sarcoma or meningioma. The results were evaluated in the context of previous immunohistochemical, ultrastructural and genetic studies and suggest that epithelioid sarcoma may be a form of malignant perineurioma with a range of differentiation (epithelial features) akin to that seen in meningioma, reflecting the close relationship between perineurium and meningothelium.

Infiltrating retiform perineurioma: a case report

Retiform perineurioma is a rare distinct histologic subtype of benign soft tissue perineurioma. We report 1 case of retiform perineurioma with a superficial invasion of the adjacent skeletal muscle. The patient was a 34-year-old woman with a neoplasm located between the deltoid muscle and the biceps. Histologically, the tumor was nonencapsulated, composed exclusively of perineurial cells without cytologic and tissue atypia. There were focal areas in which the neoplastic cells infiltrated the muscle tissue, widely separating the bundles. This case may represent a diagnostic pitfall as it can be confused with a malignant perineurioma.

Low-grade malignant perineurioma (perineurial sarcoma) of soft tissue: a potential diagnostic pitfall on fine needle aspiration

A case of low-grade malignant perineurioma presenting as a mass in the thigh is described. The patient was a 76-year-old woman with an enlarging painful mass on her right lateral thigh over the past 2 months. Thorough clinical and radiological studies did not reveal any evidence of tumor elsewhere. The patient underwent fine needle aspiration of the mass, which revealed pleomorphic spindle cells in small clusters or dispersed as single cells within myxoid stroma, cytologically consistent with a high-grade sarcoma. At surgery, the tumor was found to be entirely confined within the muscle. Grossly, the tumor measured 6.5 cm in greatest diameter and showed a gray-white fleshy cut surface that was well circumscribed but unencapsulated. Histologic examination showed a highly cellular spindle cell proliferation embedded within myxoid stroma. The tumor cells showed mild to moderate nuclear pleomorphism with minimal mitotic activity. No evidence of hemorrhage or necrosis was noted. The tumor irregularly invaded the surrounding skeletal muscle. Immunohistochemical studies showed weak membranous positivity for epithelial membrane antigen and focal cytoplasmic positivity for CD34; stains for smooth muscle actin, cytokeratin AE1/AE3, desmin, CD56, H-caldesmon, calponin, and S-100 protein were negative. Electron microscopy showed cells with thin, elongated cytoplasmic processes extending along connective tissue in a parallel, onion-like arrangement and prominent subplasmalemmal pinocytotic activity. The marked pleomorphism displayed on fine needle aspiration observed in this case can lead to a mistaken diagnosis of high-grade sarcoma resulting in unnecessarily aggressive management.